Heating system



Feb. 12, 1952 J, RQPER 2,585,591

HEATING SYSTEM Filed Oct. 21, 1948 2 SHEETS-SHEET 1 INVEN TOR. JO/Z/V/X 0, 59

Feb. 12, 1952 J, ROPER 2,585,591

HEATING sysTEM V Filed Oct. 21 1948 2 SHEETS-SI'IEET 2 INVENTOR. JO/Y/V/A P01 152? Patented Feb. 12 1952 UNITED STATES PATENT OFFICE 15 Claims.

This-invention relates to heating systems and is particularly directed to systems for converting electrical energy into steam.

This invention has for its objectsto provide new and improved heating systems. A further Object is to provide method and means for effectively and economically transforming electrical energy into steam. A further object is to provide a compact and efiicient unit for generating steam for domestic consumption. A still further objectis to provide a reversed cycle refrig eration system or heat pump of simple and efficient design which is capable of utilizing water and water vapor as the heat transfer medium. Further objects are to avoid the disadvantage of the prior art and to-obtain advantages as will appear hereinafter. Still further objects will become apparent as the description proceeds.

These objects are accomplished in the present invention of which the following is a description taken with reference to the accompanying drawing in which Figure I is a flow sheet illustrating one form of the invention and showing diagrammatically an arrangement or system of apparatus suitable.for carrying out processes according to the illustrated form of the invention. Figure II is a like flow sheet illustrating another form of the invention.

In the present invention I have provided novel and effective means and methods for generating super-heated steam by compressing water vapor instead of by the application of heat in the customary manner. Instead of burning fuel to generate steam and then super-heating it in the customary manner, I effect the generation and super-heating wholly by the application of mechanical energy through the agency of a suitable compressor in combination with suitable heat exchange devices arranged as will presently be described. By using electrical energy to provide the desired mechanical compression, I am able effectively to transform electrical energy into super-heated steam. By means of the systems about to be described I am able to do this with a high degree of efficiency and to provide steam for domestic heating purposes at a cost and with an efiiciency not heretofore possible. Thus through the systems of this invention I have made it possible for the home owner to have all the advantages which have made steam heating systems a superior heating system for larger installations without being encumbered by the disadvantages which have made it impractical to use such systems in domestic heating.

In effecting these advantages and carrying out processes according to the invention I maintain a body of water in contact with its vapor in a-closed system-such as, for example, that represented by tank i0; withdraw water vapor from said system and compress it to provide superheatedsteam as, for example, by means'of a suitable compressor, such as, thereciprocating compressor illustrated at H, the suction side of which communicates with tank In through suction line Hi; pass the thus generated superheated-steam in indirectheat exchange with said body'of water as required to transfer part of its super-heat to said body of water as, for example, by means of a suitable heat exchange coil It located in tank It and below the liquid level therein and connected with the high pressure sideof the compressor l2 through line 18; thereafter condense said super-heated steam by bringing it into direct heat exchange with a medium which it is desired to heat in a suitable heat exchange device, such as the radiator 20 arranged to heat the ambient air, which communicates with the outlet of said heat exchange coil it by means of line 22, and return the water conden'sedin the radiator to the closed system through 'theco'ndensate return 24. The system is operated so that the amount of heat transferred from the super-heated steam to said body of water is suflicient to raise the temperature of the condensate returned thereto to the temperature of said body. By this system I am able effectively to convert any form of mechanical energysuitable for driving the compressor to high pressure super-heated steam suitable for domestic heating purposes.

By means of suitable expansion valves located in the circuit for maintaining the desired pressure differential between the high and low pressure sides of the circuit I am able to establish and maintain the pressure-temperature relation desired to effect the purposes of the invention. Thus, in line 22, preferably near the outlet of the heat exchanger I6, I may locate a suitable expansion valve 26. This expansion valve opera't'es to maintain a relatively high pressure and consequently a relatively high degree of superheat in lines It and heat exchanger 16, thereby making it possible to maintain a relatively high temperature within the closed system 10. As the losses. If it is desired to forego this advantage, the expansion valve 26, of course, may be located any place in line 22 or in line 24. When it is located, as shown in Figure I, near the outlet of heat-exchanger It, it IS desirable that a second expansion valve be located either immediately beiore the radiator, as shown at 28, or some place in line 24 since it is undesirable to expand the steam all the way to the pressure existing in the closed system In before it is condensed. Thus, in a prelerred embodiment of the invention the steam is expanded adiabatically through expansion valve 2-) to some intermediate pressure and again expanded adiabatically through expansion valve 28 to the pressure existing in the closed system H3. It will be understood, of course, that still more expansion valves and more stages of the intermediate expansion may be provided if desired. For example, the steam may be expanded through expansion valve 28 to a still lower intermediate pressure and the condensate then expanded in expansion valve 36 to the operating pressure of the closed system It).

In a typical operation of a system, according to that illustrated in Figure I, water is maintained in the tank IE1 at a temperature of 170 F. and at a pressure of 6 lbs. absolute. The vapor is then compressed to a pressure of 130 lbs. absolute, whereupon its temperature will be at about 350 F. It is then expanded through expansion valve 26 to a pressure of lbs. absolute whereupon its temperature will be about 230 F. It is then expanded through expansion valve 28 and cooled in the radiator 28 to eiIect condensation. The condensate returned to the tank 10 Will be at about 80 F. and, of course, at 6 lbs. pressure absolute.

Since it is practically impossible to eifect adiabatic compression of the water vapor, still further advantages may be obtained by passing the condensate return in indirect heat exchange with the compressor, whereby some of the heat lost in the compression step is recovered and reintroduced into the system. I have found that this canbe most efiectively accomplished by arranging the system as a reverse cycle refrigeration system or heat pump wherein the waste heat of the compression is utilized as a low gradmsource of heat.

Referring now more particularly to Figure II in which like reference numerals are used to refer to parts corresponding with Figure I, there is illustrated in the condensate return line 24 a suitable heat exchanger 30 adapted to effect an indirect heat exchange between the air used to cool the motor 32 which drives the compressor l2 and the condensate being returned to the tank 10. The condensate is expanded into a suitable chamber 34 through expansion valve 36. Chamber 34 is provided with suitable fins 38 and is enclosed in a suitable jacket 40 through which the air heated by passing through the motor windings is passed by means of conduit 42 connecting the motor with the jacket 40.

By expanding the condensate in indirect heat exchange with the motor I am able to pick up a substantial quantity of the heat which would otherwise be lost in cooling the motor 32. This motor may be cooled in the usual manner by forcing a draft of ambient air through the motor windings by means of a suitable fan, not shown. The air which is thus used to cool the motor is heated to a temperature substantially above the ambient temperature and is led up through the heat exchanger as described where it loses a sub- 4 stantial proportion of its heat content to the condensate being returned to the tank.

The degree to which the condensate returned may be expanded depends upon the pressure which is maintained in the tank It. The lower the pressure which is maintained in the tank relative to the pressure over the condensate return the greater is the quantity of condensate which may be expanded. Suitable pressure differentials and operating conditions will be described in the further description of the system.

Still further waste heat of compression is recovered and reintroduced into the cycle by passing the effluent of heat exchanger 32 in indirect heat exchange with the compressor [2. This is effected suitably by means of a water jacket 44 surrounding the cylinder of the compressor. The expanded condensate is passed through line 46 into the jacket 44 and thence through line 48 to tank l6. In this manner heat which otherwise would be lost through nonadiabatic compression of the water is recovered and reintroduced into the system.

A further feature of the invention is that in times of overload as may occur on unusually cold days additional heat may be introduced into the system from some low grade source of heat such as water obtained from deep wells, the city water supply, through buried coils, or the like. This is suitably effected by means of a suitable heat exchanger 50 operated in parallel with, or, if desired, in series before (not shown), the heat exchanger 36. Thus a portion of the expanded condensate return is diverted through line 52 into heat exchanger 50, passes through the heat exchanger 50 in indirect heat exchange with water flowing into and out of the heat exchanger 50 through inlet and outlet means 54 and 56 and thence through line 58 to line 46 which carries the expanded condensate into the jacket 44. If the series arrangement is employed the condensation return will first go through the heat exchanger 50 and then through the heat exchanger 30.

In operation it is desirable that the pressure in the low pressure side be maintained below atmospheric pressure. Unlike the usual refrigeration systems employing water vapor, however, it is not necessary or desirable to maintain a high vacuum in the low pressure side. The purpose of the present invention is primarily that of transferring electrical energy into steam. Operation as a reverse cycle refrigeration circuit or heat pump is of secondary significance and is utilized primarily to recover heat which would otherwise be lost in the system or to carry the system over heat periods where the capacity would otherwise be insumcient. It is not necessary in the processes of the invention, therefore, to effect complete expansion of the condensate to water vapor and, in fact, under the conditions which applicant's system is designed normally to operate this would be undesirable because the temperatures obtained in this manner tend to cause complication due to the formation of ice in various parts of the system. I prefer, therefore, to operate my systems with the low pressure side at a pressure only slightly below the atmospheric pressure. Suitably, the pressure may range about to 1 atmosphere, preferably around about A, of an atmosphere. It will be understood, however, as illustrated above with reference to Figure I that lower pressures may be used. It will be understood, also, that if desired the pressure on the low pressure side may be maintained above atmospheric pressure. It is undesirable :to do this, "however, particularly when the steam generated is to be utilized for domestic heating purposes because of the corresponding increase in the temperature cycles. This is particularly disadvantageous when it is desired to effect transfer of heat-into the system from such low grade sources as have been mentioned above.

In atypical operation, according to the form of the invention illustrated in Figure II, the pressure in the low pressure side, i. e., in tank I6 is maintained at about 26.5 inches mercury. At this pressure the liquid water is in equilibrium with its vapor at a temperature of 206 F. The water in'tank i6 is heated to this temperature by means of a suitable submersion type electric heater 58 connected to a suitable sourceof electric power through lines 66 and 62. One Of these lines, for example line 62, is connected through av thermostatic switch 64 which is set to cut out the submersion heater 58 when the temperature of the water in tank I6 reaches the desired temperature. I

The compressor I2 now operates to withdraw water vapor from the tank [0 and to compress it to a suitable amount, say, to around 42 lbs. per square inch gauge. The water vapor is thus super-heated to a temperature of about 300 F. The super-heated steam thus produced is led through line l8 into the heat exchanger [6 where heat is given up to the water in tank I G as required to maintain the temperature at the equilibrium temperature, .for example, at 206 F. for the particular conditions here under consideration. Under thesecircumstances the pressurein tank I0 is not aiiected by the compressor I2 because water vapor is supplied from the body of water just as fast as the equilibrium is disturbed by the withdrawal of water vapor into the com pressor l2.

After passing through the heat exchanger IS the high pressure steam will be at a temperature of about 270 F. The steam is then expanded in expansion valves 2t or 28 or both in order to reduce its temperature to a safe temperature fordomestic purposes, say, to around about 180 F. and is there-condensed in radiator 20 in the process of giving up its heat to the ambient atmosphere. The condensate which is then at room temperature, say, about 70 F. or slightly above passes through line 24 to the expansion valve 36 where it is expanded to the pressure of the low pressure side; i. e., to a pressure of 26.5 inches mercury in the particular cycle being described. It will then have a temperature of about 50 F. and will consist of a mixture of condensate and water vapor. This mixture in passing through heat exchanger 30 in indirect heat exchange with the hot air from the motor 32, which will normally be about 120 F., will be heated to about 68 F. and in further passing through the water jacket 44 will be heated to about 170 F., thus showing that substantial recovery of the heat is efiected by means of heat exchanger 30 and water jacket 44.

When desired, the system may be regulated to give a still even lower temperature for the expanded condensate. This is sometimes advantageous, particularly during periods of peak load when it is desirable to provide additional heat by cutting in the heat exchanger 50. It should not be expanded, however, to a temperature much below about 34 F. if freeze-ups are to be avoided.

While I have illustrated my invention with Xeierence to domestic heating, it will be understoodthat it is applicable to otherforms ofheate ing as, for example, heating of water. Ordinarily it is most suitably applicable in heaters which effect a condensation of the steam and this is particularly true in the form of the invention illustrated in Figure II where expansion on the condensate plays an important role. It will be understood, however, that it is possible in accordance with the broader aspects of the inventionto operate a system under conditions such that the water is in the vapor state throughout.

It is within thescope of the invention to use as a diluent a non-condensable gas, such as hy drogen, nitrogen, or helium. By use of a suitable quantity of a diluent gas the total pressure may be raised without aifecting the pressure of'waterv vapor in the system. This has the advantage that, if desired, the low pressure side may :be

operated at atmospheric pressure while still maintaining the desired less than atmospheric pressure. sufficient diluent gas can be injested to reduce the partial pressure of water vapor in tank It! to 6 lbs. absolute while maintaining a total pressure of one atmosphere. bodiment of Figure II enough diluent gas can be introduced to lower the partial pressure of water vapor in tank [0 to the desired 26.5 inches mercury with a total pressureof one atmosphere.-

A further advantage is obtained in that there is less possibility of ice forming in the final expansion.

While I have described my invention with reference to particular embodiments, it will be understood that the invention is not limited in these respects but variations may be made without departing from the spirit and scope of the invention as has been set forth above and as set forth in the appended claims.

I claim:

1. A process for converting mechanical energy into heat energy which comprises maintaining a body of liquid in contact with its vapor in a closed system, withdrawing vapor from said system and compressing it to provide super-heated vapor, passing the thus generated super-heated vapor in indirect heat exchange with said body of liquid as required to transfer only part of the super-heat to said body of liquid, thereafter bringing super-heated vapor into indirect heat exchange with a medium which it is desired to heat, and returning the thus cooled product to said closed system, the amount of heat transferred from said super-heated vapor to said body of liquid being sufficient to maintain the temperature of the body of liquid without extraneous heating.

2. A process for converting mechanical energy into heat energy which comprises maintaining a body of water in contact with its vapor in a closed system, withdrawing water vapor from said system and compressing it to provide super-heated steam, passing the thug generated super-heated steam in indirect heat exchange with said body of water as required to transfer part of the superheat to said body of water, thereafter at least partially condensing said super-heated steam by bringing it into indirect heat exchange with a medium which it is desired to heat and returning it to said closed system, the amount of heat transferred from said super-heated steam to said body of water being suflicient to maintain the temperature of said body without extraneous heating.

3. The process of claim 2 in which the pressure Thus, in the embodiment of Figure I Similarly in the emover the said body of water is less than atmospheric..

4. The process of claim 2 in which the pressure over the said body of water is maintained between about and 1 atmosphere.

5. The process of claim 1 in which the total pressure over said body of liquid is substantially atmospheric and the partial pressure of vapor of said liquid is less than atmospheric.

6. The process of claim 5 in which said liquid is water and in which the partial pressure of water vapor over said body of water is between about and 1 atmospheres.

7. The process of claim 6 in which the partial pressure of water vapor over said body of water is about atmospheres.

8. A process for converting electrical energy into heat energy which comprises maintaining a body of water in contact with vapor in a closed system withdrawing water vapor from said system and compressing it with the aid of an air cooled motor to provide superheated steam, passing the thus generated super-heated steam in indirect heat exchange with said body of water as required to maintain the temperature of said body, thereafter at least partially condensing said super-heated steam by bringing it into indirect heat exchange with a medium which it is desired to heat, and returning it with at least partial expansion of the condensate to said closed system, passing air through said motor to cool it, and passing the heated air eifluent therefrom in indirect heat exchange with said expansion whereby Waste heat from said motor is reintroduced into said system.

9. The process of claim 8 in which the expansion step is effected in indirect heat exchange with said compression step whereby Waste heat of the compression step is reintroduced into said system.

10. The process of claim 9 in which indirect heat exchange is effected between the expanded condensate and a low grade source of heat whereby extraneous heat is supplied to said system.

11. The process of claim 8 in which indirect heat exchange is effected between the ex- 8 panded condensate and a low grade source of heat whereby extraneous heat is supplied to said system.

12. The process of claim 11 in which the expansion step is effected in indirect heat exchange with said compression step whereby heat which woud otherwise be lost in the compression step is reintroduced into the system.

13. A process for converting mechanical energy into heat energy which comprises maintaining a body of water in contact with its vapor in a closed system, withdrawing water vapor from said system and compressing it to provide superheated steam, passing the thus generated superheated steam in indirect heat exchange with said body of water as required to transfer part of the superheat to said body of water, thereafter at least partially condensing said superheated steam by bringing it into indirect heat exchange with a medium which it is desired to heat and returning it with at least partial expansion of the condensate in indirect heat exchange with the compression step to said body of water whereby heat which would otherwise be lost in the compression step is reintroduced into the system, the amount of heat transferred from said superheated steam to said body of water being sufficient to maintain the temperature of said body.

14. The process of claim 13 in which the pressure over said body of water is less than atmospheric.

15. The process of claim 13 in which the pressure over said body of water is maintained between about /2 and 1 atmosphere.

JOHN H. ROPER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 294,982 Foote Nov. 11, 1884 1,461,640 Wirth-Frey July 10, 1923 2,223,407 Dean Dec. 3, 1940 2,487,884 Lunt Nov. 15, 1949 

